The present invention relates to an automatic testing system for electrical transmitters, and more particularly, to such a system for testing a series of remote, normally quiescent, electrical transmitters.
In various electrical applicaitons, auxiliary systems are incorporated for indicating failure of the primary electrical function, which auxiliary systems are normally quiescent and are activated only when the primary function fails to perform properly. Because they are normally quiescent, it is necessary to periodically check their operability to be sure that they are in condition to respond to a primary function failure.
For example, in the transmission of electrical power the transmission lines are monitored for failures by a power line carrier relay system that has coordinated relays at the ends of sections of the line to mutually respond to power failure or shorting in any of the sections by energization of radio transmitter/receiver units associated with the relays that respond to power line failures occurring between the relays. However, as the carrier system is normally quiescent, it is necessary to periodically test the operability of the system, which testing is conventionally accomplished by manual actuation of local transmitter/receiver units individually at a substation to transmit signals to remote transmitter/receiver units that are energized by the signals to transmit signals back to the local transmitter/receiver units. If no signal is received by a local transmitter/receiver unit when it is being tested, it is an indication that the units are not operational and repair or replacement is required. These known carrier testing units function to individually test each transmission line carrier with a separate testing unit needed for each line, which may be multiple terminal lines, but are not capable of testing in sequence a series of transmission line carriers with a single testing unit at a common substation nor in a manner that sequences through the series of transmission line carriers and provides an indication whether any transmission line carriers in the set have failed and maintains an indication of which carrier or carriers have failed so that repairs can be made expeditiously.